Population PK-guided ATG Dosing in Haplo-HSCT

To evaluate the safety and efficacy of a population pharmacokinetics (PK)-guided targeted ATG dosing strategy in haploidentical stem cell transplantation and to observe the GVHD-free, relapse-free survival (GRFS) in the cohort receiving this strategy.

Inclusion Criteria: 1. Patients with indications for allogeneic hematopoietic stem cell transplantation, with malignant hematologic diseases in CR1 or CR2 before transplantation. 2. Have an HLA-matched sibling, unrelated, or haploidentical donor. 3. Age ≥ 14 years and ≤ 65 years. 4. Liver function: ALT and AST ≤ 2.5 × upper limit of normal, bilirubin ≤ 2 × upper limit of normal. 5. Renal function: creatinine ≤ upper limit of normal. 6. No uncontrolled infection or severe mental or psychological disorders. 7. ECOG performance status score of 0-2. 8. Signed informed consent. Exclusion Criteria: 1. No HLA-matched donor. 2. Malignant hematologic disease in CR3 or higher disease stage, or refractory/relapsed status，or second transplantation. 3. Patient age \< 14 years or \> 65 years. 4. Pregnancy of either the donor or the recipient. 5. Presence of mental illness or other conditions that preclude compliance with the protocol.